Emission regulations for internal combustion engines have become more stringent over recent years. Environmental concerns have motivated the implementation of stricter emission requirements for internal combustion engines throughout much of the world. Governmental agencies, such as the Environmental Protection Agency (EPA) in the United States, carefully monitor the emission quality of engines and set acceptable emission standards, to which all engines must comply. For example, the California Air Board (CAB) dictates a nitrogen oxide (NOx) emission standard (e.g., 30 grams NOx per hour). Consequently, using exhaust aftertreatment systems to reduce engine emissions is desirable.
Exhaust aftertreatment systems can include exhaust gas recirculation (EGR) systems that recirculate exhaust gases to an intake manifold of an engine. Additionally, exhaust aftertreatment systems can include reductant dosing systems that introduce a reductant (e.g., urea, diesel exhaust fluid (DEF), ammonia solutions, etc.) to reduce the NOx that passes through a catalyst chamber of the aftertreatment system.